bulletin: OF the geological society of AMERICA 



Vol. 29, PP. 587-600, PLS. 21-22 SEPTEMBER 30, 191S 



OOLITES m SHALE AND THEIR OEIGIN ^ 



BY W. A. TARE 



{Read before the Society December 29, 1917) 



CONTENTS 



Page 



Geology of the oolitic shales 588 



Description of the oolites 589 



General statement 589 



The oolites in the red shale 589 



The oolites in the yellow shale 591 



The oolites in the green shale 592 



Summary 593 



Origin 593 



Introduction 593 



Evidence for the theory of primary deposition 594 



Evidence against the replacement theory 595 



Source of the silica 597 



Cause of the precipitation of the colloidal silica as oolites 599 



Conclusion 600 



Geology of the oolitic Shale 



Oolites are most commonly found in limestones, dolomites, or iron ores. 

 Their occurrence in shale has not been recorded, as far as the writer is 

 aware. The oolites described in this paper are found in a shale member 

 of the red beds of the Wind River Momitains near Lander, Wyoming. 



These red beds of Wyoming owe their name to their prevailing color. 

 They consist of a series of shales, sandstones, thin beds of limestone and 

 dolomite, and some lenticular beds of gypsum. The various beds show 

 all degrees of gradation into one another, the majority being somewhat 

 calcareous. The shales are often sandy and the sandstone may contain 

 some argillaceous material. The limestone and dolomite beds are, how- 

 ever, quite pure. As this formation is very poor in fossils, its age is still 

 a matter of conjecture. Paleontologic work by Williston- and Branson^ 



^ Manuscript received by the Secretary of the Society December 29, 1917, 

 ~ S. W. Williston : .Tour. Geo!., vol. 12, 1904, p. 688. 

 3 E. B. Branson : Manuscript. 



(587) 



